1. Field of the Invention
The invention relates to a quality control method, and more particularly to a print quality control method.
2. Description of the Related Art
CMYK color printing has been widely used for many decades. The printing industry's focal point is how to achieve precise and consistent color printing. Personal judgment by highly skilled operators is required to achieve the subjective color balance control. Unfortunately it is very difficult for the printer to monitor the changes of ink level while the machine is in high-speed production. The operator can only use the trail and error method, making adjustments until reaching the closest color balance as possible. This is a costly and time consuming process by wasting large quantity of materials and extensive set up time before the actual production can begin. Because of this, printing machine manufacturers and color management equipment producers are trying to make a suitable device to measure the print operation to achieve the best finishing result. Large numbers of high cost sophisticated equipments and complicated color management controlling rods had been introduced to the market but still relying on the operator's test skills.
This is clear that the industry needs a user friendly and cost effective color adjustment method so that the operator can easily and continuously monitor the print quality and adjust the ink level as quickly as possible to achieve the high quality and speed production without using tools such as magnifying glass nor ink density reader. Reducing set up time, wastage and cost are desired to be environmental friendly.
There are many different color quality control rods available in the market. All of them can only provide a single 100% solid ink value channel of CMYK variation across the sheet to meet the standard ink density measurement. It is the only standard to achieve the elementary printing result without any data for the best neutral grey balance quality. It can only provide one of the four CMYK color data at a particular ink track. The other three-color ink densities at the same ink track become unknown data for inking adjustment. For example, across the 102 cm printing press width, there are only seven to eight ink density data for each CMYK color that can be retrieved from the job, but the machine inking console is able to provide as many as 32 ink adjustment zones. The accuracy of inking adjustment becomes as little as 25% coverage across the printed sheets; the other 75% of adjustment is trial and error. To overcome the problem, this method can provide 100% inking data for each color in overprinting conditions at any position across the full machine width without having any guessing business.